First maternal vaccine to protect infants against bronchiolitis virus approved in the U.S.

Regulatory authorities in the United States announced the approval of the first maternal vaccine that protects the baby against the respiratory syncytial virus (RSV), which causes bronchiolitis. It is applied towards the end of pregnancy and, up to the first six months of life, reduces the risk of the newborn developing severe forms of this infectious disease , which is the main cause of hospitalization in the youngest children.

Peter Marks, director of the U.S. Food andDrug Administration's(FDA) Center for Biologics Evaluation and Research, said in a statement that the approval of Pfizer's Abrysvo vaccine gives doctors and pregnant women "an option to protect babies from this potentially life-threatening disease.

The U.S. regulatory agency analyzed the effectiveness and safety results of the vaccine for the prevention of lower respiratory tract disease and its severe form caused by RSV, which is responsible for 45% of deaths between one month and the first year of life, according to the first world map of the impact of this disease that was drawn from Argentina led by the Infant Foundation.

The FDA reported today that a clinical trial of 7,000 pregnant women (half received the vaccine and half received a placebo injection) found that the vaccine "reduced the risk of severe disease by 81.8% within 90 days of delivery and by 69.4% at 180 days".

In a subgroup of women between 32 and 36 weeks of pregnancy, about 1,500 women received Abrysvo and a similar number received placebo. "Abrysvo reduced the risk of respiratory disease by 34.7% and that of severe respiratory disease by 91.1% within 90 days after birth relative to placebo," the agency said. Within 180 days, it reduced the risk of disease by 57.3% and, in its severe form, by 76.5% compared with placebo."

Safety was tested in two studies: in one, some 3600 pregnant women vaccinated with one dose of Abrysvo and 3600 who received a placebo version; in the other, the same procedure was followed in two groups of about a hundred pregnant women each. "The most common adverse effects mentioned by the participants who received Abrysvo were pain at the site of application, headache, muscle pain and nausea," the FDA recently stated.

Preeclampsia, a gestational hypertensive disorder, was detected in 1.8% of vaccinated women, compared to 1.4% of pregnant women given placebo.

The FDA, which granted fast-track approval to this Pfizer application given the need for a tool to help reduce the burden of disease and mortality associated with RSV in the very young, authorized the product for use in pregnant women between 32 and 36 weeks gestation. It is a single muscle dose.

Last May, the FDA had approved GSK Plc 's vaccine for the prevention of RSV respiratory disease in those over 60 years of age.

The impact on Argentina

Each year in the country, RSV infection causes some 20,000 hospitalizations and 600 preventable deaths in children under one year of age, equivalent to almost half of all deaths due to respiratory infections at that age, according to the study led by the Infant Foundation, a team of physicians from a dozen AMBA hospitals and the Johns Hopkins and Vanderbilt universities in the United States.

In November of last year, the results of an interim analysis of the Maternal Immunization Study for Safety and Efficacy(Matisse) had been released on the candidate vaccine at that time. They met the regulatory success criteria predefined by the FDA to the producing laboratory. The efficacy, safety, and immunogenicity (ability to generate an immune response) of the vaccine against severe, medically attended lower respiratory tract disease were evaluated in the infants of women immunized towards the end of gestation. The mothers were followed up to six months after delivery and the infants were followed up to one year of age. A subgroup of boys will be followed for two years.

At that time, Fernando Polack, scientific director of the Infant Foundation and consultant in New York for the design of the studies to evaluate this vaccine, said in an interview with LA NACIÓN: "This is the analysis that opens the evaluation of the vaccine to the FDA, the European Medicines Agency (EMA) and also the Anmat. It is the first vaccine that clearly prevents bronchiolitis, so it is of great importance in pediatrics".

In Argentina, 942 women participated in the Matisse study; most of them had already had their babies in November last year and the follow-ups, with the remaining deliveries, would be sustained throughout this year, according to the pediatrician Gonzalo Pérez Marc, one of the main investigators of the trial in the country, who coordinated four of the five participating centers in different jurisdictions. For him, who has been researching RSV with Polack for years, the results of the interim analysis already marked a before and after in pediatric care.

It is an achievement that most of the medical community still has no idea of the impact it will have," Pérez Marc told LA NACIÓN. Bronchiolitis [due to RSV] is one of the main concerns that all pediatricians in the world have every year".

Link to the original note: https://www.lanacion.com.ar/sociedad/aprueban-en-estados-unidos-la-primera-vacuna-materna-que-protege-al-bebe-contra-el-virus-de-la-nid21082023/